The chief facts already established are the greater saltness of the North Atlantic compared with the South Atlantic at all.depths, and the low salinity at all depths in the eastern equatorial region, off the Gulf of Guinea.
Later on, the opening of rapid means of transport from Kano and other cities to the Gulf of Guinea also affected Ghadames, which, however, maintains a considerable trade.
Germany had in the meantime established itself in Cameroon, and the new British protectorate extended along the Gulf of Guinea from the British colony of Lagos on the west to the new German colony on the east, where the Rio del Rey marked the frontier.
Under Alphonso V., surnamed the African (1443-1481), the Gulf of Guinea was explored as far as Cape St Catherine, and three expeditions (1458, 1461, 1471) were sent to Morocco; in 1471 Arzila (Asila) and Tangier were captured from the Moors.
The most mountainous districts lie inland from the head of the Gulf of Guinea (Adamawa, &c.), where heights of 6000 to 8000 ft.
